Scheduling comprises assigning a communication resource to a particular communication device (denoted user equipment, UE, in the following) at a given time interval. The scheduling can be done in accordance with different packet scheduling schemes. For instance, a scheduler implementing a delay based scheduling (DBS) tries to maintain given delay thresholds for traffic flows by minimizing their packet queuing delay. A scheduler implementing a proportional fair may aim at providing a guaranteed data rate for the traffic flows.
Real-time applications, such as Voice over Internet Protocol (VoIP) and video telephony, have strict delay constraints and require that the packets are sent within a certain delay budget for keeping user satisfaction. Delay based scheduling used for conversational type of traffic such as Voice over Internet Protocol (VoIP) applications or conversational video bundles together multiple packets within a packet delay budget to one transmission in order to save resources (e.g. Physical Downlink Control Channel, PDCCH, resources in case of Long Term Evolution, LTE). For a mixed traffic scenario, comprising both delay critical traffic and delay tolerant traffic, an improved throughput for best effort traffic is thereby achieved without compromising the Quality of Service (QoS) of e.g. VoIP/conversational video applications.
A number of packets are thus bundled together before transmission. In delay based scheduling, for instance, a fixed packet bundling time is used to decide when to schedule a particular UE, and the packet delay budget stipulates for how long the oldest packet of a packet bundle can be held before transmission without the QoS being compromised. When the packet is older than the packet bundling time, the corresponding UE is scheduled with absolutely highest priority in order to meet the QoS requirement. This is done by adding an extra scheduling weight bonus (weight boost) on the scheduling weight of the packet bundle, thus giving the packet a higher priority.
In minimum bit rate proportional fair, the scheduling weight is computed based on instantaneous rate, which is a data rate that the UE could potentially get, and based on an average rate for the UE.
Within wireless networks, there are time domain restrictions that may be introduced for various purposes. The communication devices may for example be configured to use a discontinuous reception (DRX) mode in order to reduce energy consumption. Besides DRX, such time domain restrictions can be introduced by features/schemes such as for instance Almost Blank Subframe (ABS) and in enhanced Inter-Cell Interference Coordination (eICIC) schemes. These features are all valuable, e.g. saving energy of the limited energy source in the case of DRX and reducing interference in the case of eICIC, but such features may also pose difficulties in view of scheduling.